Mayor Brandon Johnson on Tuesday issued a statement in response to the U.S. Environmental Protection Agency categorization of Chicago's Air Quality Index as "unhealthy" as wildfire smoke from Canada descended on the Chicago area. Johnson recommended kids, teens, seniors, people who have heart or lung disease and pregnant individuals to "avoid strenuous activities and limit their time outdoors." City officials also recommended that Chicagoans consider wearing masks, limiting their time outside, using air purifiers and closing their windows. "As these unsafe conditions continue, the City will continue to provide updates and take swift action to ensure that vulnerable individuals have the resources they need to protect themselves and their families," Johnson's statement read. "Anyone who needs immediate medical attention should dial 911."